TW565933B - Method of forming ohmic electrode - Google Patents

Abstract

There is provided a method of forming an ohmic electrode, including the steps of: forming a hafnium layer on a surface of an n type nitride-based compound semiconductor layer to have a thickness of 1 to 15 nm; forming an aluminum layer on the hafnium layer; and annealing the hafnium layer and the aluminum layer to form a layer formed of hafnium and aluminum mixed together.

Description

565933

(Ii) Brief description of the invention and the method and drawings) (The description of the invention should state: the technical field to which the invention belongs, the prior art, the content, the field of the invention. The invention belongs to the formation of a compound semiconductor formed on an n-type nitride group. An ohmic electrode on a layer, and in particular, a method for forming an ohmic electrode having a low resistance, difficult to peel an n-type nitride-based compound semiconductor layer, and providing a good ohmic contact. BACKGROUND OF THE INVENTION

Conventionally known nitride-based compound semiconductors are represented by, for example, Iηχ (} ^ Αι ^ N, which can be used as blue light-emitting devices, and X + y ^ l, and in recent years, blue light-emitting diodes, Purple semiconductor lasers and the like are being studied. These light-emitting diodes and semiconductors need to receive a current from the outside. Therefore, the ohmic electrode material provided and the technology for forming the same ohmic electrode are very important.

+ A typical ohmic pole formed on an n-type nitride-based compound semiconductor layer is disclosed, for example, in Japanese Patent Publication No. 7-45 867. The electrode is a stack of titanium ( Ding) and an aluminum layer (αι) are formed and annealed as an ohmic electrode (hereinafter referred to as "Ti / Al electrode,"). In addition, in the Proceedings of the 60th Anniversary Conference of the Applied Physics Society, 3 ( ) 2 pages (speech report No. n14) Report σ with excellent thermal stability of Ti / A1 electrodes and an ohmic electrode that allows annealing in a wide temperature range of 400 ° C to 600 ° C. According to the report, The ohmic electrode is formed of a hafnium (Hf) layer formed on an n-type nitride-based compound semiconductor layer and an αι layer stacked on the hafnium layer (hereinafter referred to as a "Hf / Al electrode"). However, the Hf / Al electrode reported above was formed by stacking HfAAi.

Use special controls to include Hf and A1 content of the right # 3 in the far electrode. So make it

The Hf / Al electrode has a non-smooth surface and provides poor contact with the n-type nitride-based "〇 物 半 '" layer, so as to have a high resistance. In addition, the 4 clad electrode can be peeled off the semiconductor layer and therefore Unable to provide good ohmic contact. Summary of the invention In view of the above, the present invention carefully considers a method of forming an ohmic electrode with a low resistance, difficult to peel a type 11 nitride-based compound semiconductor layer, and providing a good ohmic contact. The invention provides a method for forming an ohmic electrode, comprising the following steps: forming a hafnium layer on a surface of an n-type nitride-based compound semiconductor layer to have a thickness of 1 to 15 nm; forming an aluminum layer on the hafnium layer And annealed the hafnium layer with the aluminum layer to form a layer formed by hafnium and mixing. Please note that in this specification, "〇 / 〇" stands for "% by mass". The foregoing and other objects, aspects, features, and advantages of the present invention will become more apparent when the following detailed description of the present invention is combined with the accompanying drawings. A brief description of the figure is in the drawings: Figure 1 represents the resistance between an interface adjacent region between the Hf content and a compound semiconductor layer interposed between an n-type nitride group and Hf and A1. A relationship; FIG. 2 is a schematic cross-section of a light emitting nitride-based compound semiconductor device according to a first example; FIG. 3 represents the measurement of a semiconductor compound of a light emitting nitride-based compound according to the first example (3) 565933 One of the results of the current-voltage characteristics between the ohmic electrodes provided by the bulk device; Figure 4 is a schematic top view of a first example of a light-emitting nitride-based compound semiconductor device; Figure 5 A schematic cross-section of a light-emitting nitride-based compound semiconductor device as a second example; FIG. 6 is a schematic cross-section of a light-emitting nitride-based compound semiconductor device as a third example; FIG. 7 is a third example A schematic top view of a light-emitting nitride-based compound semiconductor device; FIG. 8 is a schematic cross-sectional view of a light-emitting nitride-based compound semiconductor device that is being manufactured as a fourth example; FIG. 9 is a completed first Four examples A schematic cross-section of a nitride-based compound semiconductor device; FIG. 10 is a schematic cross-section of a fifth example of a light-emitting nitride-based compound semiconductor device; FIG. 11 is a light-emitting nitrogen of a sixth example being manufactured A schematic cross-sectional view of a compound semiconductor device based on a chemical compound; and FIG. 12 is a schematic cross-section view of a light-emitting nitride-based compound semiconductor device completed as a sixth example; Detailed description of the drawings The present invention provides one ohm An electrode having an Hf content of less than 0.001% to less than or equal to 50% and an area of less than or equal to an interface adjacent region between a compound semiconductor layer of a ^ -type nitride-based compound and the ohmic electrode

565933 50% to less than or equal to 99.999% of A1 content. This situation and the present invention are found from the following resistance measurement and energization test results; resistance measurement An ohmic electrode formed of AI and Hf is fabricated on a surface of an n-type GaN semiconductor. Figure 丨 represents a relationship between the content of the intermediary KHf and the resistance of a region adjacent to the interface between the 0-type nitride-based compound semiconductor layer and the ohmic electrode. In Figure 1, the horizontal axis represents content (mass percentage) and the vertical axis represents resistance. ⑴Sample preparation A spot electrode consisting of an ohmic electrode spaced 500 μm apart and arranged on one surface of a silicon-doped GaN semiconductor was provided as a sample. The ohmic electrodes are formed by secondarily depositing an Hf layer on a silicon-doped GaN semiconductor and an A! Layer to have a thickness of 150 nm2 on the Hf layer and then annealing at the same temperature for two minutes at the same temperature. . For each sample, the thickness of the Hf layer was changed from 0.5 nm to 150 nm to allow the Hf content to be less than one interface adjacent to the interface between the n-type nitrogen-based compound semiconductor layer and the ohmic electrode. The range is from 0.001% to 90%. (ii) Method of resistance measurement Resistance is calculated by increasing the -voltage until a current of 50 mA flows when a current flows between adjacent point electrodes of each sample. (iii) Measurement results As shown in Fig. 1, samples with a small content of KOOi% 2Hf in the vicinity of the interface provide south resistance. In addition, samples with Hf content greater than 50% in the vicinity of the interface also provide high resistance. In these cases, some of the interfaces between (5) (5) 565933 between the n-type nitride-based compound semiconductor layer and the point electrodes did not provide sufficient ohmic contact. In addition, a sample having Hf content in the vicinity of the interface of less than 0.0001% to less than or equal to 50% has no change in resistance and has low resistance between any two-point electrodes. Please note that the above Hf content measurement is provided using a secondary ion mass spectrometer (SIMS), an electronic microprobe (EPMA), or the like. Power-on test: The sample is one of the light-emitting nitride-based ohmic electrodes in an area adjacent to an interface between an n-type nitride-based compound semiconductor layer and the ohmic electrode and having an HfR capacity of less than 0.001%. Compound semiconductor devices, and light emitting nitride-based compound semiconductor devices having one of the ohmic electrodes having an Hf content of more than 50% and an ohmic content of less than 5000 / 002A1 in the vicinity of the interface were provided as samples. (ii) Power-on test procedure At atmospheric pressure, the samples were energized at a current of 30 for 5,000 hours. At the same time, the surface condition and peeling of each ohmic electrode and the luminescence and similar conditions of each sample were observed. (i i i) Test results Samples with Hf content less than 0.001% were previously attenuated and lost ohmic contact, such as peeling and impaired reliability. Samples with Hf content greater than 50% and A1 content less than 50% between the n-type nitride-based compound semiconductor layer and the ohmic electrode -10 · 565933

The mask has an insufficient contact portion, and the ohmic electrode has a very rough surface. Therefore, the sample is weakened in reliability. From these results, it was found that an interface between an ohmic electrode formed on a surface of an n-type nitride-based compound semiconductor layer and an intermediate electrode layer between the n-type nitride-based compound semi-body layer and a helium electrode It is preferable that the adjacent area has an Hf content of less than 0.001% to 50% and an A1 content of less than 50% to 99.999%. This is because it is believed that in order to obtain a good contact between an ohmic electrode and an n-type nitride-based compound semiconductor layer, the electrode needs to have a specific amount of Hf and a specific amount of contact A1 with the semiconductor layer. In addition, it has also been found that the Hf & Al content of the ohmic electrode can be easily formed by forming an Hf layer on a surface of an n-type nitride-based compound semiconductor layer to have a thickness of 1 to 15 nm and forming a μ layer It is controlled to fall within the above range on this layer. example

The following example is used to more specifically illustrate a light emitting nitride-based compound semiconductor device using the ohmic electrode of the present invention. First Example Referring to FIG. 2, a first example provides a sapphire substrate, a buffer layer, a compound semiconductor layer of an n-type nitride group, an ohmic electrode, a rhenium electrode, an n-type electrode, A light emitting layer 7, a yoke-type cladding layer 8, a type 1 contact layer 9, a p-type ohmic electrode 10, a p-type pad electrode, and a light-emitting nitride-based compound semiconductor device of one of the transparent conductive films 12. The light emitting nitride-based compound conductor device of the first example is manufactured as described below. -11 · 565933

缓冲 A buffer layer 2 is formed on a sapphire substrate 1 and an 11-type nitride-based compound semiconductor layer 3 on the layer is formed of GaN doped with silicon (Si). Thereafter, the multiple quantum well light emitting layer 7 on the semiconductor layer 3 is formed of a barrier layer formed of GaN and a well layer formed of InGaN. The light-emitting layer 8 is formed of AlGaN doped with magnesium (Mg). The 1) -type contact layer 9 on the p-type cladding layer 8 is formed of GaN doped with Mg. A p-type ohmic electrode iq is formed on the p-type contact layer 9 by vapor-depositing a 7 nm thick (Pd) layer. On the p-type ohmic electrode 10, a p-type pad electrode ^ is formed of a 15 nm2Pd layer and a gold (Au) layer having a thickness of 500 nm is formed thereon. The p-type pad electrode is formed by vapor deposition using a metal mask. A light emitting area is formed later. More specifically, a photoresist is applied to the p-type ohmic electrode 10 and the p-type pad electrode, and the p-type ohmic electrode 10 is etched with a hydrochloric acid-based etchant in a photoresist-free portion to form a light-emitting pattern. . The photoresist is then removed. Sn-doped Iri203 (ITO) transparent conductive film 12 is formed to cover a portion of a surface of a p-type pad electrode U and a p-type ohmic electrode 10 by sputtering. And a part of the transparent conductive film 12 is etched with a vaporized iron-based solution. Thereafter, a photoresist is used as a mask for a dry etching and a reactive ion etching (RIE) is used to etch the intermediate product to expose a surface of the semiconductor layer 3. The ohmic electrode 4 is then formed by peeling. More specifically, the photoresist is uniformly applied to the exposed semiconductor layer 3 and the photoresist is removed to provide a window on a portion where the ohmic electrode 4 will be provided. It then includes a Hf layer with a thickness of 5 nm and a thickness of 565933 formed on the Hf layer.

Eighty 150 nm layers are formed by peeling to have a width of 10 μm on the exposed surface of the semiconductor layer 3. The Hf layer and the Hf layer are then annealed at 500 ° C. for 3 minutes in a vacuum to form eight mixed regions in the vicinity of the interface between the ohmic electrode 4 and the semiconductor layer 3. Fig. 3 represents a result of measuring one of the current-voltage characteristics between the ohmic electrode 4 and the ohmic electrode 4 of the luminescent nitride-based compound semiconductor device of the first example to confirm the ohmic contact. It has been found that good ohmic contact is obtained.

Hf and A1 are mixed together at an interface adjacent area between the semiconductor layer 3 and the ohmic electrode 4, as already explained, and have been found to be between one of the 11-type nitride-based compound semiconductor layer 3 and the ohmic electrode 4 The adjacent area of the interface contains approximately 0.5% of Hf and approximately 99.5% of A1. From a Pd layer with a thickness of 15 nm and formed there? A non-ohmic pad electrode 5 formed of an A1 layer having a thickness of 500 nm on 4 layers is then formed on the ohmic electrode 4 by vapor deposition to form an n-type electrode 6. The non-ohmic osmium electrode 5 allows a current to be sufficiently introduced so that a low-voltage driven luminescent nitride-based compound semiconductor device can be manufactured. After that, the substrate 1 is grounded and polished to have a thickness of approximately 100 μm and a square divided into 350 μm X 350 μm and an Au line (not shown) is bonded to the p-type pad electrode 11 and the pad electrode 5 to complete a luminescent nitrogen Chemical compound semiconductor device. Fig. 4 is a schematic top view of one of the light-emitting nitride-based compound semiconductor devices thus manufactured. In addition, the light-emitting nitride-based compound semiconductor device thus manufactured may be -13-565933

It is driven with a voltage of 3.0 V. -A low-voltage driven light-emitting nitride-based compound semiconductor device can therefore be manufactured. In addition, the light-emitting device was subjected to a power-on test and the device did not have an electrode such as peeling after a 10,000-hour period had passed, and it has been found that it will have high reliability. Although the n-type nitride-based compound semiconductor layer 3 has been formed of GaN doped with it, it may be formed of, for example, Si-doped inGaN. In addition, 'Although the ohmic electrode 4 has been initially formed by forming a layer on the semiconductor layer 3 and then forming an A1 layer on the layer, it can be initially formed by forming an A1 layer on the semiconductor layer 3 and thereafter It is formed on this layer. Second Example In the first example, the Hf and A1 layers were provided by vapor deposition and then annealed in a vacuum to form an ohmic electrode with the Hf and A1 layers mixed together. In the second example, when a Hf layer or an eighteen layer is deposited, a wafer is heated to form an electrode having a layer in which Hf and A1 are mixed together. Referring to FIG. 5 ′, the first example provides a sapphire substrate 21, a buffer layer 22, an n-type gasification-based compound semiconductor layer 23, an ohmic electrode 24, a pad electrode 25, an n-type electrode 26, and a light emitting device. A layer 27, a p-type cladding layer 28, a p-type contact layer 29, a p-type ohmic electrode 110, a p-type pad electrode m, and a light-emitting nitride-based compound semiconductor device of one of the transparent conductive films 112. The light emitting nitride-based compound semiconductor device of the second example is manufactured as described below. -14- 565933

(ίο) The same procedure described in the first example is followed until the intermediate product is dry-etched to expose one surface of the semiconductor layer 23. The ohmic electrode 24 is then formed by peeling. More specifically, the photoresist is uniformly applied to the exposed semiconductor layer 23 and the photoresist is removed to provide a window on a portion where an ohmic electrode 24 will be provided. Later, a wafer was heated to 80 degrees Celsius before flying deposition. Since the circle is maintained at 80 degrees Celsius, an Hf layer is deposited to have a thickness of 3 mm, and an A1 layer is deposited to have a thickness of 150 nmw and peeling is utilized to form the same in the semiconductor layer 23 The exposed surface has a width of 10 μm to form an ohmic electrode 24. The current-voltage characteristics between the ohmic electrodes 24 are measured and similar to the characteristics of the first example. It has been found that heating a wafer during vapor deposition can eliminate the need for annealing, as illustrated in the first example, to provide a low-resistance one-ohm electrode. One of the interface adjacent areas Hf and A1 between the ohmic electrode 24 and the semiconductor layer 23 is mixed together, and it has been found that the interface adjacent area between the semiconductor layer 23 and the ohmic electrode 24 contains approximately 0.5% Hf and The steps of forming a non-ohmic pad electrode 25 in an amount of approximately 99.5% and the subsequent steps are similar to those of the first example. In addition, the light-emitting nitride-based compound semiconductor device thus manufactured can be driven with a voltage of 3.0 V. A low-voltage driven light-emitting nitride-based compound semiconductor device can therefore be manufactured. In addition, the light-emitting device was subjected to a power-on test and after being subjected to 100,000--15-565933

After the hour period, the device did not peel off an electrode, for example, and has been found to have high reliability. In addition, although the electrode 24 has been initially formed by forming a layer on the semiconductor layer 23 and then forming an A1 layer on the layer, it can be formed by forming an A1 layer on the semiconductor layer 23 and thereafter. The Hf layer is formed on this layer. A third example is shown in FIG. 6. This third example provides an ohmic electrode 34, a substrate 31, a buffer layer 32, an n-type nitride-based compound semiconductor layer 33, a light-emitting layer 37, and a p-type substrate. The cladding layer 38, a p-type contact layer 39, a p-type ohmic electrode 210, a p-type pad electrode 211, and a transparent conductive film 212 are a light emitting nitride-based compound semiconductor device. The light emitting nitride-based compound semiconductor device of the second example is manufactured as described below. On the n-type GaN sapphire substrate 31, a buffer layer 32 and a silicon (Si) -doped GaN n-type nitride-based compound semiconductor layer 33 are formed in this order. On this layer, the multiple quantum well light emitting layer 37 is formed of a barrier layer formed of GaN and a well layer formed of InGaN. On the light-emitting layer ^ is the cladding layer 38 formed? AlGaN is formed. On the p-type cladding layer "upper-type contact layer 39 * p-type" is formed. On one surface of the p-type contact layer 39, a p-type transparent ohmic electrode 210 is vapor-deposited with a palladium (Pd) layer having a thickness of 6 nm. Formed. The p-type ohmic electrode 210 is annealed in a vacuum at 500 ° C for 3 minutes to process the p-type contact layer 39 and the p-type ohmic electrode 210 to provide an alloy. A photoresist is then applied on the p-type ohmic electrode 210 and Decision Zone -16- 565933

The domain photoresist was removed. The p-type ohmic electrode 21 is etched in a photoresist-free portion with a hydrochloric acid-based etchant to form a light-emitting pattern. The photoresist was then removed. A 1) -type bonding pad electrode 211 is formed on a part of the p-type ohmic electrode 210. More specifically, the photoresist is uniformly applied to the p-type ohmic electrode 210 and the pi contact layer 39 and the photoresist is removed to provide a Windows. A stack of one layer and one eighth layer on the Pd layer are formed by vapor deposition to have a thickness of approximately 1 μm on the exposed p-type ohmic electrode 210 and peeling is used to remove edge photoresist Stack on the agent to form a p-type pad electrode 2 1 1. After the p-type pad electrode 211 is formed, a transparent conductive film 212 of ιτο is formed by depositing a substrate at 25 ° C on a p-type ohmic electrode 2 and a portion of the p-type 塾 electrode 211 It has a thickness of approximately 100 nm. After that, the photoresist is applied to the transparent conductive film 2 12 and the photoresist is removed from a predetermined area and the transparent conductive film 2 12 located in the photoresist-free portion is engraved with a ferric chloride-based solution. Carved by shoes. After that, the photoresist is removed. Please note that the transparent conductive film 212 is etched in this way except that it partially covers one end of one upper surface of the p-type 塾 electrode 211, one side surface of the p-type ohmic electrode 21, and part of the p-type contact adjacent to the p-type ohmic electrode 210 Except for a portion of the layer 39 and the exposed portion. One Hf layer with a thickness of 5 nm on one of the back surfaces of the substrate 31 is then provided by vapor deposition and one A1 layer with a thickness of 200 nm on this layer is provided by vapor deposition and then they are in vacuum at Celsius 500 degree annealing for 3 minutes to -17-565933

(13) Form ohmic electrodes 34. The back surface of one of the ohmic electrode 34 and the substrate 31 has an interface in which Hf and A1 are mixed together, and it has been found that the vicinity of the interface between the substrate 31 and the one of the ohmic electrode 34 contains approximately 1% of Hf and approximately 99% of A FIG. 7 is a schematic top view of a light-emitting nitride-based compound semiconductor device manufactured in this manner. Although the p-type ohmic electrode 21 is formed of a pa layer in the third example, it may be formed of any metal or alloy that allows a thin transparent film to be formed. In addition, although the transparent conductive film 2 丨 2 has been formed of IT0 in the third example, it may be additionally composed of at least one selected from zinc (Zη), indium (Ιη), tin (butylη), and town (Mg). , Cadmium (Cd), gallium (Ga), and lead (Pb). In addition, 'Although the light emitting layer 37 has been a barrier layer formed of GaN and a multiple quantum well formed of a well layer formed of InGaN in the third example, it may be a single quantum well or it may be AlGalnN, GaAs , GaNP, or any four- or three-base mixed crystal. Further, although the n-type nitride-based compound semiconductor layer 33 is already si-doped GaN, it may be formed of, for example, siiInGaN. In addition, 'Although the ohmic electrode 34 has been initially formed by forming an Hf layer on a back surface of the substrate 31 and then forming an eighteen layer on this layer, it can be initially formed by forming an A1 layer on the substrate A Hf layer is formed on one of the back surfaces and after that on the layer. Fourth example -18- 565933

(14) As shown in FIG. 8, the epitaxial growth wafer includes a substrate 41, a buffer layer 42, a n-type nitride-based compound semiconductor layer 43, a light-emitting layer 47, a p-type cladding layer 48, A p-type contact layer 49, a p-type ohmic electrode 310, gold, a basic electrode 13, and a light emitting nitride-based compound semiconductor device holding one of the metal layers 14. As shown in Fig. 9, the substrate 41 is then removed and an ohmic electrode 44 is formed on the buffer layer 42 to complete a light emitting nitride-based compound semiconductor device. The light-emitting nitride-based compound semiconductor device of the fourth example is manufactured as specifically described later. Initially, as shown in FIG. 8, the n-type buffer layer 42 of InAIN and the n-type nitride-based compound semiconductor layer 43 of Si doped GaN are formed in this order on the Si substrate 41 and GaN is formed on the layer. A barrier layer formed and a multiple quantum well light emitting layer 47 formed of a well layer formed of InGaN are stacked. A p-type cladding layer 48 is formed on the light-emitting layer 47 from p-type AlGaN. A p-type contact layer 49 on the p-type cladding layer 48 is formed of p-type GaN. A layer is provided on the p-type contact layer 49 by vapor deposition to form a p-type ohmic electrode 310 having a thickness of 10 nm and the kneads are annealed at 500 ° C for 3 minutes in a vacuum to process the pd layer and The p-type contact layer 49 provides an alloy. On the p-type ohmic electrode 31, an Au layer having a thickness of 300 nm is provided by vapor deposition to form a gold-plated, basic electrode 13. On the electrode 13, a retaining metal layer 14 formed of Ni and having a thickness of ⑽μm is provided by electrolytic bonding gold. The substrate 41 is then removed. More specifically, an upper surface of one of the metal layers 14 and a side surface of a wafer excluding the substrate 41 are covered with electronic wax. Hydrofluoric acid, acetic acid and nitric acid are mixed together at a ratio of 5: 2 ... 2 and used as a -19- (15) (15) 565933

The etchant dissolves and thus removes the substrate 41 to expose one surface of the buffer layer 42. The electronic wax is removed with acetone or any other similar organic solvent. Then, referring to FIG. 9, a 51 ^ thick 1 ^ layer and then a 200 nm thick A1 layer are provided by vapor deposition on the surface of the buffer layer 42 and annealed at 500 degrees Celsius in vacuum: > Ohmic electrode 44 is formed. The buffer layer 42 and the ohmic electrode 44 have an interface where Hf and A1 are mixed together, and it has been found that the adjacent area of the interface contains approximately 5% of Hf and approximately 95 ° /.量 的 A1。 The amount of A1. Finally, the intermediate product was cut into small cubes having a size of 300 μm × 300 μm. Although the p-type ohmic electrode 3 has been formed of pd in the fourth example, it may be formed of any metal or alloy that can provide a p-layer ohmic electrode. Further, although in the fourth example, the retaining metal layer 14 is formed of Ni by an electroless bond, it may be formed of any metal that conducts electricity, and it may be formed by a technique other than A-phase deposition and electric money. For example, it may be a simple fixed conductive plate. In addition, in the fourth example, although the light-emitting layer 47 has been formed as an I1 early shielding layer formed of GaN and a multi-quantum well formed as a well layer formed by In GaN, it may be a single quantum well and may be A1GaInN, GaNAs, GaNPs or any four-based or three-based mixed crystal. In addition, although in the fourth example, the substrate 41 has been formed of Si, it may be any substrate that is easy to etch and also allows a nitride-based compound semiconductor layer to be formed. Further, although the semiconductor layer 43 is already Si-doped GaN, it may be formed of, for example, Si-doped InGaN. -20- 565933

(16) In addition, although the ohmic electrode 44 has been initially formed by forming an Hf layer on the buffer layer 42 and then forming an A1 layer on the buffer layer, it can be initially formed by forming an A1 layer on the buffer layer 42 An Hf layer is formed on and after this layer. Fifth Example Referring to FIG. 10, a fifth example provides an ohmic electrode 54, a substrate 51, a buffer layer 52, an n-type nitride-based compound semiconductor layer 53, a crack prevention layer 15, and an n-type coating. Layer 16, an n-type optical guiding layer 17, a light-emitting layer 57, a p-type carrier block layer 18, a p-type optical guiding layer 19, a p-type cladding layer 58, a p-type contact layer 59, A p-type ohmic electrode 410 and a nitride-based compound semiconductor laser device of a dielectric film 20. The nitride-based compound semiconductor laser device using the electrode of the present invention is manufactured as described below. Initially, a GaN buffer layer 52 was formed on the n-type GaN substrate 51 at a low temperature to have a thickness of 100 nm. An n-type GaN n-type nitride-based compound semiconductor layer 53 is then formed on this layer to have a thickness of 3 µm. Next, a 40 nm thick In07Ga9N n-type crack prevention layer 15 is formed. Next, a thickness of 0.8 μm is used to form an AlOiGa ^ N n-type cladding layer 16. Next, a 0.1 μτη thickness is formed, and a GaN n-type optical guide layer 17 is formed. After that, the light emitting layer 57 is formed by stacking a 4 nm thick, GaN〇97P0.03 well layer and an 8 nm thick three-layer barrier layer. After that, the light-emitting layer 57 was 20 nm thick, and an Al 2 Ga 0 sN ρ type carrier block layer 18 was formed. On this layer, a thickness of 0.1 i is formed, and a GaNp-type optical guiding layer 19 is formed. On this layer, 0.5 μm thick, an AloiGaoWp type cladding layer 58 is formed. -21- 565933 (17) The humor is clear. On this layer, a GaN p-type contact layer 59 is formed to a thickness of 0.1 μm. Although the above description has been provided in conjunction with the GaN substrate 51iC plane {00〇〇1}, the orientation of the main plane of the substrate can be the A plane {11-2〇}, the R plane {1-1 02}, and the M plane {1 -1 〇〇} or {卜 1〇1} plane. In addition, any substrate having a compensation angle within two degrees of the above orientation has been found to provide good surface texture. Although the above description substrate 51 has been formed of GaN, it may be an n-type nitride-based compound semiconductor substrate other than GaN. For nitride-based compound semiconductor laser devices, it is preferable to allow a vertical lateral mode to be a single peak, and a layer having a refractive index smaller than that of a coating layer is adjacent to the outer side of the other coating layer, An AlGaN substrate is suitable for use. A procedure for obtaining a nitride-based compound semiconductor laser device will now be described. The ohmic electrode 54 is formed by vapor-depositing a Hf layer having a thickness of 5 nm on a back surface of the substrate 51, and then vapor-depositing a layer having a thickness of 2000-A1 on the layer, and then in a vacuum. It was formed by annealing the same at 500 ° C for three minutes. One of the rear surfaces of the electrode 54 and the substrate 51 has an interface in which Hf is mixed with A1 and it has been found that the vicinity of the interface contains approximately 3% of Hf and approximately 97% of A1. The p-type ohmic electrode 410 is engraved along a line of the nitride semiconductor crystal <M00> direction to form a ridge line Rs. The ridge line Rs is formed to have a width of 2 μm. Thereafter, the dielectric film 20 of SiO 2 is provided by vapor deposition. After that, the p-type contact layer 59 is exposed. After that, the exposed p-type contact layer 59 is -22- (18) (18) 565933

On the dielectric film 20, a Pd layer, then a Mo layer, and then an Au layer are provided by vapor deposition to form a p-type ohmic electrode 41. Alternatively, the p-type ohmic electrode 410 may be sequentially vapor-deposited for the Pd, Pt, and Au layers, or a Pd layer and an Au layer may be provided on the Pd layer by vapor deposition or provided by vapor deposition. A Ni layer and an Au layer are formed on the Ni layer. Finally, a split plane of the substrate 51 is utilized to provide a Fabry-P6rot resonator with a hole length of 500. The Fabry-Pdrot resonator is provided with a mirror end face, which in turn provides 70 ° / by alternating vapor deposition. Reflectivity, Si02 and Ti02 dielectric films to provide a multi-dielectric reflective film. Although an electrode is formed on a back surface of the substrate 51 when the ohmic electrode 54 is formed in the fifth example, it may be formed by using dry etching to expose the semiconductor layer 53 on the front side of one epitaxial wafer and It is formed by forming an ohmic electrode 54 on the exposed surface. In addition, although the ohmic electrode 54 has been initially formed by forming an Hf layer on a back surface of the substrate 51 and then forming an A1 layer on the layer, it can be initially formed by forming an A1 layer on an n An Hf layer is formed on the substrate and thereafter. A sixth example is shown in FIG. 11 'An epitaxially grown wafer includes a substrate 6, a buffer layer 62, an n-type nitride-based compound semiconductor layer 63, a light-emitting layer 67, and a P-type cladding layer. 68. A p-type contact layer 69, a p-type ohmic electrode 510, gold, a basic electrode 113, and a light emitting nitride-based compound semiconductor device holding one of the metal layers 114. As shown in Figure 12, the substrate 61 and the layer 61 are subsequently moved -23- 565933

(19) A ohmic electrode 64 is formed on the n-type nitride-based compound semiconductor layer 63 to complete a light-emitting nitride-based compound semiconductor device. The nitride-based compound semiconductor laser device using the electrode of the present invention is manufactured as described below. Initially, as shown in FIG. 11, an A1N n-type buffer layer 62 and a Si-doped GaN-type nitride-based compound semiconductor layer 63 on a Si substrate 61 are formed in this order and formed of GaN on the layer. One of the barrier layers and the multiple quantum well light emitting layer 67 formed of one well layer formed of InGaN are stacked. A p-type cladding layer 68 * p $ A1GaN is formed on the light emitting layer 67. The p-type cladding layer "upper-type contact layer 69 is formed of p-type GaN. On one surface of the p-type contact layer, a pd layer is provided by vapor deposition to form a p-type ohmic electrode 510 having a thickness of 50 nm2 and They were annealed in vacuum at 50 ° C for 3 minutes to process the% layer and the P-type contact layer 69 to provide an alloy. On the p-type ohmic electrode 51, an Au layer with a thickness of 300 nm was passed through the vapor phase. Deposition is provided to form a gold-plated, basic electrode 113. On the electrode 113, a retaining metal layer 114 formed of Ni and having a thickness of 100 ^^^ is provided by electrolytic gold plating. The substrate 61 is subsequently removed. More specifically, An upper surface of one of the metal layers 114 and a side surface of the wafer excluding the substrate 61 is covered with an electronic wax. Hydrogen acid, acetic acid, and lithocholic acid are mixed at a ratio of 5: 2: 2 and used as a nicking agent. The substrate 61 is dissolved and thus removed to expose one surface of the buffer layer 62. The electronic wax is removed with acetone or any other similar organic solvent. The buffer layer 62 is then dry-etched to expose one surface of the semiconductor layer 63. After that As shown in FIG. 12, in the semiconductor layer 63 A surface of the upper layer and the Hf -⑽ are simultaneously formed to provide ohmic electrical iv * having a thickness of -24-565933

(20). The Hf layer and the A1 layer were annealed in a vacuum at 500 ° C for 3 minutes. The ohmic electrode 64 includes Hf and A1 mixed together and an interface adjacent region between the semiconductor layer 63 and an ohmic electrode 64 has been found to contain approximately 5% of Hf and approximately 95% of A1. Finally, the intermediate product is cut into small cubes with a size of 300 μm X 300 μm. Although the p-type ohmic electrode 5 1 0 has been formed of Pd in the sixth example, it may be formed of any metal or alloy that can provide a p-layer ohmic electrode. In addition, although in the sixth example, the retaining metal layer 1 1 4 is formed of Ni by an electroless boat, it may be formed of any metal that conducts electricity, and it may be formed by a technique other than vapor deposition and electroplating. For example, it may be a simple fixed conductive plate. In addition, although in the sixth example, the light-emitting layer 67 has been a shielding layer formed of 0aN and a multiple quantum well formed of a well layer formed of InGaN, it may be a single quantum well and may be AlGalnN, GaAs, GaNP is any four-based or three-based mixed crystal. In addition, although in the sixth example, the substrate 61 has been formed of s i, it may be any substrate that can be easily carved and also allows a nitride-based compound semiconductor layer to be formed. Although the semiconductor layer 63 is already doped with GaN, it may be formed of, for example, Si-doped InGaN. In the present invention, as explained above, an n-type nitride-based compound semiconductor layer is not limited as long as the material is formed of a material represented by InxGayAl ix yN, where OSd, 〇 $ # i and x + y $ , The η-type nitrogen-25- 565933

(21) Chemical-based compound semiconductor layers are stacked by a conventionally known technique such as a vapor-phase house crystal, a molecular beam insect crystal, or the like. In addition, the n-type nitride-based compound semiconductor layer of the present invention, as described above, and an ohmic electrode formed on the layer has an interface in which Hf and A1 are mixed together, and may have the Hf and A1 mixed with additional metals. An interface 0 In addition, the ohmic electrode can also be provided to the n-type nitrogen by base plating, vacuum deposition, vapor deposition, electron beam vapor deposition, or any other similar conventional known technology, or a combination of technologies. On a compound semiconductor layer. In addition, although annealing is performed after a Hf layer is formed on the n-type nitride-based compound semiconductor layer and an A1 is provided on the layer, it may be selected when the Hf layer and the A1 layer are formed. It is performed by heating the semiconductor layer. In addition, in addition to the Hf layer and the A1 layer, which can be provided on the n-type nitride-based compound semiconductor layer, it is obvious from the above description that the present invention can provide a providing and Ohmic electrode with superior contact for nitride-based compound semiconductors. The present invention can thus provide a high production yield of a compound semiconductor device with a low voltage and two reliable light emitting compounds. Although the present invention has been described and explained in detail, it is clearly understood that the same situation is only for explanation and example and is not a limitation. The spirit and scope of the present invention are limited by the patent application project. ^ Explanation of Symbols of the Drawings-26- 565933 (22) Bu 21 Sapphire substrate 2, 22, 32, 42, 52, buffer layer 62 3, 23, 33, 43, 53, n-type nitride compound semiconductor layer 63 4, 24, 34, 44, 54 ohm electrodes 5, 25 塾 electrodes 6, 26 n-type electrodes 7, 27, 37, 47, 57, light-emitting layer 67 8, 28, 38, 48, 58, ρ-type coating Layer 68 9, 29, 39, 49, 59, ρ-type contact layer 69 10, 110, 210, 310, P-type ohmic electrode 410, 510 11 ^ 111 &gt; 211 ρ-type pad electrode 12, 112, 212 Transparent conductive film 31, 4 51, 61 substrates 13, 113 gold plating, basic electrodes 14, 114 metal layer 15 η-type crack prevention layer 16 η-type coating layer 17 η-type optical guide layer

-27- 565933 (23) 18 19 20 P-type carrier block layer P-type optical guide layer Dielectric film -28-

Claims (1)

565933, patent application scope 1. A method for forming an ohmic electrode, the method includes the following steps: forming a given layer on a surface of a type nitride compound semiconductor layer to have a thickness of 1 to 15 nm Forming an aluminum layer on the hafnium layer; and annealing the hafnium layer and the aluminum layer to form a layer made of hafnium and aluminum mixed together.